Progressivism has always been premised on the notion that man has a changeable nature and thus is able to achieve perfection during his time on earth. As a result, progressives consistently maintain that government is responsible for transforming men and women into perfect creatures. They develop programs and reforms suited not for man as he is, but for man as he ought to be (and, progressives would argue, for man as he could become, with the right societal structures).
Against that idea, most religious believers contend that man is flawed by his very nature and incapable of perfecting himself without the help of God, and that perfection is in fact unattainable during earthly life. While sects and denominations differ vastly, religion itself — and indeed any dependence on a Creator — is a direct contradiction to the progressive conception of man as changeable and perfectible.
In short, progressivism and religion — understood as a fundamental reliance on God rather than on oneself or on other men — are inherently incompatible.
Democrats’ Religion Problem: Progressivism & Faith Inherently Contradictory | National Review